Sewing hook and bobbin



Nov. 4, 1969 L. PRESTON I 3,476,068

SEWING HOOK AND BOBBIN F iled Aug. 15. ,1967 2 Sheets-Sheet 1 E 2i 2 Z 2; 2 mm 2 2'5 2 /3 7 I T 2 a I jj /7 5 Zaiil j/ a 27/ F G 2 F T I F I 21." l INVENTOR. I LOUIS PRESTON ATTORNEYS Nov. 4, 1969 L. PRESTON 3,476,068

snwms noox AND BOBBIN 2 Sheets-$heet Filed Aug. 15, 1967 V III/111111! 11:45 m m AQMK ATTORNEYS United States Patent 3,476,068 SEWING HOOK AND BOBBIN Louis Preston, Brooklyn, N.Y., assignor to Miracle Hook Corp., New York, N.Y., a corporation of New York Filed Aug. 15, 1967, Ser. No. 660,688 Int. Cl. D051) 57/16 US. Cl. 112-231 4 Claims ABSTRACT OF THE DISCLOSURE An improved sewing hook and bobbin which eliminates the bobbin case and rotatably mounts the bobbin in the sewing hook with the sewing hook carrying means for applying friction to the bobbin to place tension on the bobbin thread during sewing, with the tension being independent of the type or thickness of the thread. The sewing hook is also of improved design whereby sewing at a higher speed is permitted without causing a burning of the thread looped over the sewing hook.

BACKGROUND OF THE INVENTION This invention relates generally to an improved sewing hook and a bobbin for sewing machines. In prior art devices, the bobbin is mounted in the hook by means of an intermediate bobbin case through which the bobbin thread extends. The opening in the hook is limited by the dimensions of the hook and the bobbin and bobbin case must be designed to be received in the opening in the hook. The size of the bobbin is thus limited by the presence of the bobbin case which must surround the bobbin and be received in the opening in the bobbin hook thereby making the bobbin smaller than would otherwise be desirable since an increase in bobbin size would allow more thread to be wound on the bobbin to permit an increase in the number of stitches that may be sewn before replacement or rewinding of the bobbin is required.

In the prior art devices, tension is applied to the bobbin thread during sewing by applying a frictional pressure to the thread by a suitable device which presses the thread against the outside of the bob'bin case. For any particular setting of the device, the tension will vary between various threads based on the parameters of thread diameter and frictional qualities of the thread material. Thus for each different type or size of thread, the friction device must be adjusted to obtain the optimum tension on the bobbin thread.

During the sewing operation, the thread fed by the needle is caused to loop around and pass over the sewing hook and, at high speed, the thread sliding across the surface of the hook tends to heat up and could burn if sewing takes place at an excessive rate of speed. Thus the speed of sewing is effectively limited as a result of the possible heating and burning of the thread.

Thus, while prior sewing hooks and bobbins have operated satisfactorily, restrictions have necessarily been placed on speed of sewing, tension adjustment and bobbin capacity.

SUMMARY OF THE INVENTION Generally speaking, in accordance with the invention, an improved sewing hook is provided which eliminates an intermediate bobbin case and thereby allows full use of the opening in the element mounted in the sewing hook for receiving the bobbin. By eliminating the intermediate bobbin case, the bobbin can be of a greatly increased size with a resultant substantial increase in thread capacity. Since very large spools can be mounted for carrying the thread advanced by the needle, continuous sewing in commercial operations is constantly interrupted for replace- 3,476,%8 Patented Nov. 4, 1969 pick-up of the bobbin thread before sewing can begin as required with conventional apparatus.

The invention also contemplates the application of a frictional drag force directly to the bobbin instead of to the bobbin thread to thereby make the tension independent of thread size and material.

The invention further contemplates an improved design of 'the sewing hook to permit the thread to more easily slide thereover during the looping operation which results in a substantial increase in sewing rate without damage tothe thread as a result of burning.

Accordingly, it is an object of this invention to provide an improved sewing hook and bob'bin whereby uninterrupted sewing can be accomplished at a faster rate and for a longer period of time as compared with prior art devices.

Another object of the invention is to provide a sewing hook and bobbin apparatus wherein the bobbin may be directly carried by a bobbin support in the sewing hook without being supported in an intermediate element.

Another object of the invention is to provide a sewing hook and bobbin construction wherein the bobbin has a substantially increased capacity as compared with prior art arrangements.

Still another object of the invention is to provide a sewing hook and bobbin assembly wherein the tension applied to the bobbin thread is independent of the thread size or material.

Another object of the invention is to provide a sewing hook having improved sewing characteristics whereby sewing may take place at a faster rate.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawings, in which:

. FIG. 1 is an elevational view of a sewing hook and 'bobbin constructed in accordance with one embodiment of the instant invention;

FIG. 2. is a sectional view taken along line 22 of FIG. 1 showing the bobbin assembled to the hook in full lines and withdrawal from the hook in phantom lines;

FIG. 3 is a sectional view taken along line 33 of FIG. 1;

FIG. 4 is an exploded perspective view of the bobbin and bobbin support shown in the previous figures;

FIG. 5 is an elevational view of another embodiment of the instant invention; and

FIG. 6 is a sectional view taken along line 66 of FIG. 5 with portions thereof being shown in exploded view and by means of phantom lines.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 thorugh 4, a sewing hook indicated generally at 11 is mounted on or includes a shaft 12 by which the sewing hook is rotated. The sewing hook includes a casing 13, which may be of generally standard construction. Casing 13 includes a hook 14 of the known type which picks up the loop of thread 15 from the needle 16 in order to form the stitch in cooperation with bobbin thread 17. Mounted to the outside of casing 13 is a curved plate 18, which may also be of known construction, which also carries a hook 19 proximate to the main hook 14 to define therebetween a slot 21 which receives thread 15 during the looping of the thread over the bobbin thread as shown in FIG. 1. Casing 13 rotates in the direction indicated by arrow A.

A bobbin support 22 having cylindrical walls and being closed at one end is provided with an annular projection 23 received in a raceway groove 24 in the cylindrical wall of casing 13 to provide for relative rotation between the bobbin support and casing 13. In Operation, bobbin support 22 remains stationary and casing 13 rotates about the bobbin support as a result of rotation of shaft 12.

In the embodiment shwon in FIGS. 1-4, a central tube 25 projects upwardly from an end wall of bobbin support 22 and has pivoted thereto a lever 26 which may rotate between the full line position shown in FIG. 2 for applying a frictional drag force to a bobbin, as will be hereafter described, and the phantom line position wherein the bobbin may be inserted in or removed from the opening defined by the cylindrical walls of bobbin support 22. A spring 27 and a plate 28 are mounted within central tube 25 for applying a resilient pressure ot one end of lever 26 to bias the other end toward the bobbin.

The bobbin is indicated at 31 and is similar to known bobbins except that it is of substantially larger size than previous bobbins capable of being mounted in a sewing hook of equal size. Bobbin 31 has a central opening 32 through which the bobbin is rotatably mounted on tube 25. The bobbin is symmetrical and has end walls 33, one of which engages the bottom wall of bobbin support 22. The other end wall is engaged by an adjusting screw 34 to apply a frictional drag to the bobbin by the contact pressure between screw 34 and end wall 33 as a result of the pressure applied to lever 26 to resiliently maintain it in the full line position shown in FIG. 2 by spring 27. It can be seen that rotation of adjusting screw 34 will selectively increase or decrease the pressure and thus the frictional drag force on the bobbin, as may be desired for the proper sewing operation. It will be seen that the drag force applied to the bobbin is completely independent of the bobbin thread 15 and thus tension on the bobbin thread will not be a variable based on thread diameter or thread material.

It should be noted that casing 13 and bobbin support 22 are elements found in existing sewing hooks with the opening defined by the cylindrical walls of the bobbin support defining the limit of size of elements that may be mounted therein. In the prior art, a bobbin as well as a bobbin casing must be received in said opening thereby reducing the permissible diameter and width of the bobbin. In the invention described herein, elimination of the bobbin case by directly mounting the bobbin within the bobbin support permits the bobbin to have a greater diameter and width and thus a substantially greater capacity. Thus the bobbin will require rewinding or replacement at longer intervals to increase the efliciency of the sewing operation.

As shown in FIGS. 1 and 4, the outer peripheral edge of bobbin support 22 is provided with a radially directed groove 35 through which the bobbin thread extends and by which the bobbin support is guided for proper orientation within the sewing machine. It is again noted that the bobbin support remains stationary during the sewing operation.

As best shown in FIG. 3, bobbin support 22 is provided with a radially directed aperture 36 through which needle 16 may project at the end of its downward travel during formation of the loop which will be picked up by hook 14. The provision of a groove 35 and an aperture 36 in the bobbin support is likewise known in the art.

However, the configuration of the peripheral edge of bobbin support 22 is a substantial departure from prior arrangements and a substantial improvement thereover whereby the machine can be operated at a greatly increased speed. As will be understood by those skilled in the art with reference to FIG. 1, book 14 draws thread through needle 16 as it rotates and forms a large loop which is passed around bobbin thread '17 in order to form the stitch which is drawn tight when the needle reciprocates to its raised position. As appears in FIG. 1, development of the loop of thread 15 requires that it slide over the bobbin support and bobbin and development of the surface of the peripheral edge of the bobbin support, at least during the formation of the loop by the rotating hook will greatly improve the operating characteristics. The developed surface is indicated at 41 and is perhaps best seen in the perspective view of FIG. 4. The leading or outermost edge of developed surface 41 extends outwardly a sufficient distance to cause the thead to clear over the outer end wall of bobbin 31. The critical area of the developed surface extends from groove 35 for about in the advancing direction of hook 14 or in other words during the portion of hook travel during which the loop of thread 15 is being increased in size and thus must slide over developed surface 41. The remaining configuration of developed surface 41 is less critical since, after hook 14 has traveled 180, the loop of thread will fall free and be drawn back by return movement of the needle. For ease of understanding, a phantom line has been drawn perpendicular to the central axis of bobbin support 22 in FIG. 4. The critical development of surface 41 is the surface area generally to the left of the phantom line while the area generally to the right of the phantom line is not deemed critical.

Developed surface 41, in the critical area, slopes off sharply from its projecting edge 42 to a line 43 at or below the level of hook 14, as may be seen in FIG. 2. The major portion of the critical surface may slope along a straight line or be slightly convex except at the initial portion of formation of the loop where the surface is preferably slightly concave as indicated at 44 in FIG. 4. Developed surface 41, for a substantial portion of the area to the left of the phantom line in FIG. 4 slopes at an acute angle which is preferably less than 45 with respect to the cylindrical wall defining the opening in the bobbin support. With the sloping surface, thread 15, during development of the loop, can slide smoothly over the developed surface with minimum drag and without engagement with a sharp edge or surface. Thus the heating of the thread as a result of the sliding action is greatly reduced as compared with prior art arrangements and thus the machine may be operated at a greatly increased speed, all to the benefit of efficiency of operation.

Referring now to FIGS. 5 and 6, an alternate embodiment for applying a friction drag force to the bobbin is disclosed with means also being provided for ejecting the bobbin from the bobbin support. The construction of the various elements is generally the same as described in connection with P168. 1 through 4 and the description of the embodiment of FIGS. 5 and 6 will be limited to the differences in construction. As between the two embodiments, like numerals refer to like parts.

In the embodiment of FIGS. 5 and 6, a central post 51 replaces central tube 25. The central post is provided with a longitudinal hole 52 having threads 53 proximate to the outer end thereof and a cam surface 54 at the base thereof. The cam surface slopes toward a slotted aperture 55 in the wall of the central post. A pin 56 having a cam shaped projection 57 at one end thereof is slidably received in longitudinal hole 52 with the cam shaped projection extending through slotted aperture 55. The opposite end of pin 56 carries a post 58 over which is mounted a spring 59. One end of the spring bears against the end shoulder of pin 56 and the other end is received in a screw 61 thread into the central post.

With screw 61 threadedly engaged in the central post, spring 59 biases pin 56 toward the bottom of hole 52 and, by cooperation with cam surface 54, cam shaped projection 57 is caused to be biased to extend outwardly through slotted aperture 55.

Bobbin 31 is the assembled position as shown in FIG. 6, is received over central post 51 and the wall of the central opening 32 in the bobbin is engaged by projection 57 to urge the projection and the pin carrying same into hole 52. In this manner, by cooperation between the wall of the bobbin and projection 57, a frictional drag force is applied to the bobbin to thereby impart tension to the bobbin thread as it is unreeled from the bobbin during the sewing operation. It is immediately apparent that, by rotation of screw 61, the friction force applied to the bobbin can be selectively increased or decreased. As in the previous embodiment, the tension applied to the Bobbin 31 in the assembled position as shown in FIG. bobbin thread is a function of the drag force placed on the bobbin and is independent of bobbin thread diameter or material.

If desired, a bobbin ejecting device, indicated generally at 62, can be mounted to bobbin support 22 for partial ejection of the bobbin so that it may be grasped and withdrawn. The bobbin ejecting device is composed of a lever 63 pivoted intermediate its ends as at 64 to the bobbin support and an ejecting arm 65 is pivoted at one end, as at 66, to one end of lever 63. The other end of arm 65 projects proximate to the interior surface of one of the end walls 33 of the bobbin and, on rotation of lever 63 to the phantom line position shown in FIG. 6, the bobbin can be driven outwardly so that it may be physically grasped. A spring 67 surrounding pivot 66 acts between the lever and ejecting arm to bias the bobbin ejecting device to the full line position shown in FIG. 6.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of languge, might be said to fall therebetween.

What is claimed is:

1. A sewing hook and bobbin for a sewing machine comprising a casing, a bobbin support, mounting means cooperating between said casing and said bobbin support for rotatably mounting said bobbin support in said casing, said bobbin support having an opening therein, a bobbin rotatably mounted in said opening in said bobbin support, and friction means carried by said bobbin support and acting between said bobbin support and said bobbin for applying a frictional drag force to said bobbin, said friction means including means for adjusting the frictional drag force applied to said bobbin, said bobbin occupying substantially the entire volume of said opening in said bobbin support, said bobbin support including a central post over which said bobbin is rotatably mounted and said friction means being carried by said central post and having a portion thereof adapted to engage a surface of said bobbin, said central post having an aperture therein and said friction means including a lever pivoted to said central post and having an end thereof projecting into said aperture in said central post, a spring received in said aperture and acting against said end, and means proximate to the other end of said lever for engagement with a surface of said bobbin, said means applying a frictional drag force to said bobbin as said bobbin rotates about said central post.

2. A sewing hook and bobbin as claimed in claim 1 wherein said last mentioned means includes means for adjusting the frictional drag force applied to said bobbin.

3. A sewing hook and bobbin for a sewing machine comprising a casing, a bobbin support, mounting means cooperating between said casing and said bobbin support for rotatably mounting said bobbin support in said casing, said bobbin support having an opening therein, a bobbin rotatably mounted in said opening in said bobbin support, and friction means carried by said bobbin support and acting between said bobbin support and said bobbin for applying a frictional drag force to said bobbin, said friction means including means for adjusting the frictional drag force applied to said bobbin, said bobbin occupying substantially the entire volume of said opening in said bobbin support, said bobbin support including a central post over which said bobbin is rotatably mounted and said friction means being carried by said central post and having a portion thereof adapted to engage a surface of said bobbin, said central post having an aperture therein and said friction means including a pin slideably received in said aperture in said central post, said aperture having a cam surface at the base thereof communicating with a slotted aperture in a wall of said central post, said pin having a cam-shaped projection cooperating with said cam surface and adapted to project through slotted aperture for engagement with a surface of said bobbin, and means acting against said pin for biasing said cam-shaped projection outwardly of said slotted aperture.

4. A sewing hook and bobbin as claimed in claim 3 wherein said last named means includes a screw threadedly received in said central post and spring means acting between said screw and said pin for applying an adjustable resilient force to said pin for adjusting the drag force applied to said bobbin by said pin.

References Cited UNITED STATES PATENTS 1,096,369 5/1914 Hohmann 112'231 1,105,197 7/1914 Hohmann 112231 1,182,842 5/1916 Erickson 112-188 1,351,869 9/1920 Petti 1l2231 1,702,383 2/1929 Hemleb 112-188 2,555,658 6/1951 Ritter 1122'29 3,050,021 8/ 1962 Fukushima 112229 573,894 12/ 1896' Miller.

875,603 12/ 1907 Parkes.

HERBERT F. ROSS, Primary Examiner US. Cl. X.R. 112-181 

